The Numerical Study of Heat and Mass Transfer during the Condensation Process within the Indoor Unit of a Split-Type Air-Conditioner

• Main Authors: Chun-Hsiung Lin, 林群雄
• Other Authors: Shih, Yang-Cheng
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/998y4k

碩士 === 國立臺北科技大學 === 能源與冷凍空調工程系 === 106 === In recent years, the global warming effect causes the electric power consumption of the air-conditioning in the tropical and subtropical area to increase dramatically. Therefore, how to reduce the power consumption of air-conditioning has became a very important issue. The split-type air conditioner (SAC) is widely used in a household and an office because of its compact size, smooth appearance, low noise, and easy to adjust the volume flow rate. In order to improve the performance of air conditioners, this study adopted the Computational Fluid Dynamics (CFD) software-ANSYS FLUENT to analyze the internal flow field and the heat transfer performance of the indoor unit of a SAC. This study developed a theoretical model for the two-dimensional numerical simulation of the indoor unit of a small-sized SAC. The compact fins of the evaporator were treated as a porous zone composed of the air and aluminum fins. To simulate the thermal performance of the evaporator, the non-equilibrium thermal model was used to predict the temperature distributions of the aluminum fins and the air respectively. The VOF (Volume of Fluid) model was adopted to simulate the behavior of the liquid water and wet air (composed of dry air and water vapor) during the condensation process occurring on the evaporator. To predict the condensation rate on the evaporator, the Fickian law, Lee Model equation and Mass Transfer equation was employed in this study. Incorporating the evaporator with the dynamic rotation of the cross-flow fan (CFF), numerical simulation predicted the velocity, temperature and water vapor fields, condensation rate, and the heat transfer performance of the evaporator of the indoor unit. Moreover, the volume flow rate of the SAC, the total heat transfer rate of the evaporator, and absolute humidity at the discharging outlet predicted by the numerical method were also compared with experimental results. The relative errors between both results were less than 9%, revealing that both results agreed well and the model developed in this study was accurate.